Method of and apparatus for recovering metals



Feb. 19, 1935'. w LOCKE 1391 763 METHOD OF AND APPARATUS FOR RECOVERING METALS Filed Sept. 30, 1953 3 Sheets-Sheet 1 /NZ/EN 77.72% F.- w LOCKE- flTTER/VE/ Feb. 19,1935. F. w. LOCKE 1,991,763

METHOD OF AND APPARATUS FOR RECOVERING METALS Filed Sept. 30, 1955 3 Sheets-Sheet 2 v *TUA/Ey I F. W. LOCKE METHOD OF AND APPARATUS FOR RECOVERING METALS Feb. 19, 1935.

Filed Sept. 30, 1953 3 Sheets-Sheet 3 12 nw/ /v 70 F: w. LOCKE:

Patented Feb. 19, 1935 PATENT OFFICE METHOD OF AND APPARATUS FOR. RECOVERING METALS Frank W. Locke, Portland, reg., assigner, by directandmesne assignments, to Coast Mining Company, Portland, Greg. 1

Application- September 30, 1933, Serial No. 691,705

sclairns. (Cl.'20415) This invention relates generally to the recovery of metals from ores and particularly to a method of and apparatus for the recovery of precious metals. a

The main object of this inventionisto increase the rapidity of the decompositionof ores in the presence of an electrolytic solution.

The second object is to strip ores electrically for the purpose of exposing the metals therein to 0 the action or" the electrolytic solution without materially dissipating the energy of the solution onmaterials which are worthless or whose recovery is not being sought. i

Before entering into, a description of this invention it will be understood that gold-and other metals have long been extracted from certain ores by treating same with a dilute solution of potassium cyanide, the dissolved metal being; afterward precipitated by zinc or electrically, after which it is fused and cast into ingots.

This process, while satisfactory in; many instances, is notpractical, for example, in the recovery of gold, platinum and other precious metals from what is commonly; termed-- black sand, since, although the cyanide solution will; act upon the black sand the process is ex tremely slow and muchof the solutions strength is expended upon materials not intended to be recovered- In the process I am about to describe and the apparatus by means of which the process is practised, a weak cyanide solution is employed in the presence of an electric current which is made to flow through the sand while passing through the solution.

These and other objects will become more apparent in the specifications following as illustrated in the accompanying drawings in which:

Fig. 1 is an elevation of the apparatus showing portions thereof broken away in vertical sections.

Fig. 2 is a plan of Fig. 1.

Fig. 3 is a'section taken along each of the lines 33 in Fig. 2

Fig. 4 is a section taken along the line 4-4 in Fig. 2.

Fig. 5 is a section taken along the line 5-5 in Fig. 1.

Similar numbers of referencerefer to the same or similar parts throughout the several views.

Referring in detail to the drawings there is shown a stripping tank whose top side is open.

and whose bottom 11 slopes toward a narrow outlet 12 in which is mounted a rotatable gate Between the sidewalls 16 of the stripping tank 10 is rotatably mounted a shaft 1'7 on which is secured the strippingdrum- 1'8 whichhprovided with. radial fins 19 on its outer surface and flanges 20 on its outer ends for the purpose of forming pockets into which the blacksand 21 can fall from an overhead hopper 22, whoseoutlet 23' is also provided with rotatable gate 13 which is driven bya sprocket wheel 24.

On the shaft 17 is secured a sprocket wheel 25. A chain 26 passes around the sprockets 15, 24 and 25 as well as around the driving sprocket 27 of the gear reducer 28 towhich power is supplied by a motor 29' through the chain 30. Current is suppliedtothe motor 29 through the lead wires 31 under the control of a motor switch-32. The stripping drum 18 comprises the cathode of the device and is made of metal, the kindof which is determined by the particular conditions surrounding the recovery. v

On' the side walls 16 are formedthe notches 33 which determine theposition of the transverse rod 34 which is an electrical conductorand from which hang a plurality of anodes-'35 preferably separated by the rubber insulators 36 which are spaced along therod 34. A low voltage current" is carried to the rod 34 bymeans of, a wire 3'? which includes a low voltage control switch- 38 and voltmeter 39. i p

The shaft 17 is electrically connected by means of the wire 40 to the power circuit 41.

It will be understood that in practice a motor generator set is employed to provide the relatively low voltage current between the anode 3,5 and the cathode 18, whereas the motor 29 is preferably operated at voltages normally used for such purposes, but for the sake of simplifying the diagram the current for the stripping process is illustrated as coming directly from the regular power line. a

An ammeter 42 is connected to the wires 40.

Adjacent to the stripping tank 10 is an overflow and storage solution tank 43 which is connected to the tank 10 by means of an overflow pipe 44 by means of which a constant liquid level in the tank 10 may be limited to merely insure the complete submerging of the stripping drum 18.

Above the storage tank 43 is carried a reserve solution tank 45 from which cyanide solution 46 is permitted to flow by gravity through a pipe 4'7 into the stripping tank 10. Under the control of a valve 48 the solution 46 may also pass from the tank 45 to the tank 43 through the pipe 49 under the control of the valve 50, Any

other suitable electrolyte 46 may be employed.

An elevated fresh water tank 51 supplies water to the tank through the pipe 52 under the control of the valve 53. A solution is circulated from the tank 43 to the tank 45 through the pipe 54 by means of a pump 55 under the control of a valve 56. The pump .55 is operated by a motor 5'7 whose lead wires 58 contain a control switch 59 and are joined to the power circuit 41. The power circuit itself is provided with a main control switch 60.

Sand is added to the hopper 22 by means of a suitable conveyer 61 after it has been suitably screened to remove large particles and foreign substances.

Underneath the outlet 12 is placed a receiving tank 62 into which the broken down materials or sludge 63 are gathered and subsequently separated by any of the well known methods not illustrated or described herein.

'It will be understood that while this invention relates particularly to the stripping of the ores, the complete process, of course, includes the final separation of the recovered metals from the residue. p

The operation of the device is as follows:

Assuming that there is a supply of black sand 21 within the hopper 22 and that this sand contains precious metals which are to be recovered and that there is a weak solution of electrolyte in the stripping tank 10 and that a current is ilowing from the anode 35 to the cathode 18 and that the cathode or stripping drum 18 is being rotated as indicated in Fig. 1, it will be seen that the sand from the hopper 22 will fall upon the drum 18 and lodge between the radial fins 19 and be carried around in a manner to crossthe current flowing from the cathode 35 to the anode 18, which action in the presence of the electrolyte brings about a rapid and complete stripping-or breaking down of the black sand particles, reducing them to a sludge 63 which is precipitated upon the tank bottom 11 and finally discharged from the outlet 12 by the gate 13 into the tank 62 or other collector where it is ready for final separation.

It is apparent from an inspection of the drawings that no difficulty is experienced in maintaining the solution to the desired level and density and that the current flow may be regulated to a nicety by varying the position 01' the rod 34 which naturally varies the amount 01' resistance offered to the flow of the current to the cathode 18.

While I have thus illustrated and described my invention,.it is not my intention to be limited to the particular details of construction illustrated in the drawings, but I intend to cover all such forms and modifications thereof as fall fairly within the appended claims. The use of the term black sand includes any comminuted ore.

I claim:

1. An apparatus for stripping ores having in combination a cathode consisting of a revolvable stripping drum having pockets formed around its exterior cylindrical surface, an electrolyte tank in which said drum may be submerged while being rotated, anodes disposed within said tank opposite said drum, means for rotating said drum so that the side nearest the anode will turn downwardly, and means for supplying comininuted ore to the pockets on the top side of said drum whereby the rotation of said drum will cause said ore to travel across the path of current flowing from said anode to said cathode.

2. An apparatus of the class described, the combination of an electrolyte tank having a sloping bottom provided with a revol'vable outlet gate'at a low point thereof, a cathode consisting of a revolvable stripping cylinder mounted within said tank constituting a means for carrying ore downwardly through said solution,

anodes in said tank on the down turning side of said cylinder from which current can flow through the electrolyte in said tank through the downwardly passing ore, and means for varying the rate of flow of said current from said anode to said cathode. i

3. The device describedin claim 2, together with means for maintaining the required electrolytic solution within said tank, and means for removing the sludge formed when said current passes through said ore, said sludge constituting a seal at the outlet opening of said electrolyte tank.

FRANK W. LOCKE. 

